PROJECT SUMARY / ABSTRACT Flaviviruses are single-stranded RNA viruses, including dengue virus (DENV) and Zika virus (ZIKV), with disease severity ranging from uncomplicated febrile illness to more severe symptoms including neuronal complications like Guillain-Barr syndrome or encephalitis. Each year >100 million individuals worldwide suffer from flavivirus- induced illness. Our understanding of the molecular and tissue-specific pathogenesis of flaviviruses remains incomplete and few therapeutic options exist to diagnose or effectively treat these pathogens. RNA viruses, such as flaviviruses, deliver their genetic information via a long RNA molecule, and despite this being the main unit if infectivity, relatively little is known about its direct role in pathogenesis; rather most research has focused on the proteinaceous output of the RNA. The viral genomic RNA (gRNA) molecule itself acts as a functional hub inside host cells to control pathogenesis, however few molecular details of this activity are well characterized. One well described feature, in particular for flaviviruses, is the translation of the gRNA at the surface of the endoplasmic reticulum, a key mammalian organelle. Thus, this project aims to systematically dissect the molecular mechanism of viral RNA recruitment to the ER surface (Aim 1) which will reveal insights in viral and host translation at the ER. It also aims to characterize preliminary results which suggest that host factors important for ER-membrane curvature and trafficking associate with the viral gRNA. In this way Aim 2 will define the mechanism by which these host COPI complex contributes formation and or function of viral replication factories. Finally, it aims to discover the tissue-specific and in vivo host factors associated with the ZIKV gRNA (Aim 3), developing a key resource to understand how the virus leverages each infected organ in an infected animal. Taken together, this project will provide an unprecedented molecular view of Zika, and more generally flaviviral biology from the perspective of their RNA genomes, which will nominate novel host proteins for therapeutic targeting. The proposed work will be performed under the co-mentorship of Dr. Carolyn Bertozzi, and expert in developing chemical biology tools to study infectious diseases, and Dr. Jan Carette, a leader in genome-wide methods to identify host networks hijacked by RNA viruses, both at Stanford University, a world-class research institution. Aims 1 and the initial part of Aim 2 and 3 will be performed during the K99 mentored phase while the functional validation of hits identified in Aim 2 and 3 will be performed during the R00 independent phase. This award, if funded, will allow me to pursue a rigorous training plan along novel avenues of research to learn new techniques, develop new skills, and acquire new knowledge, which together will accelerate my transition to an independent research position where I will focus on fundamental mechanisms of RNA bases diseases like viral infections.